The broad objective of the proposed project is to understand the association of anxiety, stressful life events (SLE), and physical health in late life. Little research has been conducted on anxiety in older adults, although anxiety disorders are more prevalent than affective disorders in this age group. Among adults, anxiety is associated with high prevalence of illness, disability, excessive health care usage and poor quality of life. Less is known about the impact of anxiety on the physical health of older adults. The proposed research aims at (1) understanding the temporal association of anxiety, SLE, and physical illness in late life;(2) testing whether anxiety and SLE increase the risk of death in older adults;and (3) understanding genetic and environmental influences underlying these processes. The study will draw from a sample of reared-apart and reared-together twins from a large scale population twin registry. Self-report data on anxiety, SLE and physical health were collected through questionnaires at 8 occasions over a 20-year period;linkage to national registries will further provide data on hospitalization records and mortality. Temporal association will be examined with latent difference score (LDS) structural equation models. Compared to the commonly used cross-lagged or growth curve models, LDS models allow us to evaluate whether increases in (versus mean levels of) anxiety and SLE are predictive of later onset of physical illness, and vice versa. Calculation of mortality risk due to anxiety and stressful life events after adjusting for potential covariates will be performed with survival analysis. Analyses will be performed at both phenotypic and genotypic levels to estimate the effects of anxiety and SLE on illness and mortality after partialling genetic influences. This project directly addresses the research priorities stated by the National Institute on Aging and the Healthy People 2010 initiative: understanding late-life anxiety and its impact on morbidity and mortality are necessarily to improve prevention, diagnosis and intervention of these comorbid conditions. Prevention, diagnosis and intervention efforts can in turn prolong active life and health expectancies in older adults, and reduce unnecessarily costs due to excessive service utilization, medications and impairment in the later half of life.